Dry Forest
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Of course, you've heard of tropical rainforests, but have you ever heard of a tropical dry forest?

Hi I'm Bryan Yeaton, and this is the Weather Notebook.

Triangular palm Neodypsis decaryi, Madagascar. Mark Olson Photos

In Costa Rica some forests there get no rain at all for half the year. Correspondent, Allan Coukell reports.

For six months of the year it's lush and green and gets as much rain as a tropical rainforest. For the other half of the year the plants and animals of Costa Rica's dry forest survive with almost no rain at all. The trees of the dry forest respond to the long annual drought by dropping their leaves, just like temperate forests, further north, lose their leaves in winter. John Sullivan is an ecologist who's worked in the dry forest.

"They don't have any leaves, but it's also the time when they make their fruits and flowers. They don't necessarily appear dead. There's all sorts of exciting things that go on in the dry season that don't occur in the wet season.

The dry forest is low and scrubby, but in terms of the diversity of plants and animals it's just as complex as the rainforest. Dr. Sullivan says it's an exciting place to be.

"It's fabulous. There's so much going on in a tropical forest everyday, everytime you go out there to do your field work you see a lot of different things. You see a different insects, discover a different plant, you see monkeys over here and all sorts of things. It's just really, really entertaining. There's stuff going on all the time, it's like living in a nature documentary"

But the climate of the dry forest is also well suited to agriculture and much of the forest has been burned to make way for farming. Today, only about two percent of the original dry forest remains.

Alan Couckell lives in Auckland, New Zealand. The Weather Notebook is produced by the Mount Washington Observatory with support from the National Science Foundation.